You can't unlock the pipelines as there aren't anymore to unlock (you have 8). You can overclock the GPU and the memory though, assuming your starting from 500/900, 550/1000 should be easily achievable depending on cooling.
dude, a word of caution. I've oc'd quite a few 6600gt's, pcie and agp, and have yet to see one stable at 600mhz. i suggest u check for stability at anything higher than 540 at stock cooling, and then increment at 5 mhz intervels. Dont fry your card so early.
